Hydraulically operated vibrator soil compactor



June 17, 1969 5, BE|ERLE|N ET AL 3,450,012

HYDRAULICALLY OPERATED VIBRATOR SOIL COMPACTOR Filed March 8, 1968 INVENTORS BERNHARD BEIERLEIN ULRCH BEJEKLENv BY THEIR ATTORNEY.

United States Patent US. C]. 9448 11 Claims ABSTRACT OF THE DISCLOSURE A soil compactor or tamper is hydraulically operated and the hydraulic system comprises an oil tank which is substantially flat and parallel to the ground for distributing the tamping weight as evenly as possible over the area covered by the tamper.

The invention relates to tampers, for example, of the types shown in our Patent No. 3,280,712 and in the Patent No. 3,342,118 by one of us.

In present vibration soil compactors or tampers which are hydraulically operated and comprise a driving motor, for example, an electric motor or an internal combustion engine driving a pump for raising the pressure of circulated oil which drives a vibration producer, for example an imbalanced wheel, the hydraulic system comprises an oil tank of considerable weight which must be properly coordinated with other weights or masses, for example the driving motor, the hydraulic pump and, possibly, a steering gear or handle bar. It has been found difficult to effect this coordination satisfactorily.

In conventional soil tampers of the kind with which the invention is concerned, the aforesaid masses are arranged on a support plate which is connected by resilient means to parts of the tamper which are in contact with the ground to be compacted, namely a tamping plate or tamping rollers. All these masses must be so distributed on the support plate that the static load is substantially evenly distributed throughout the extent of the base of the tamper.

In conventional soil tampers wherein it is essential that the static masses are evenly distributed, complicated structures must be provided in order to obtain a correct, namely even, weight distribution.

It is accordingly among the principal objects of the invention to provide a soil tamper of the soil plate or roller type which avoids the structural difiiculties inherent in conventional tampers.

It is another object of the invention to provide a sup port plate that is arranged to serve also as the oil tank of the hydraulic system.

Further objects and advantages of the invention will be set forth in part in the following specification and in part will be obvious therefrom without being specifically referred to, the same being realized and attained as pointed out in the claims hereof.

Broadly speaking, the hydraulic oil tank of the instant invention is preferably coextensive with the area covered by the ground contact means of the tamper, and extends at least over a substantial part of the area occupied by the masses resting on the plate-like oil tank. Therefore, the oil tank has large surface areas and provides a much greater heat radiation than conventional oil tanks; cooling means that are necessary in conventional tampers can be dispensed with, and less oil is required for driving the vibration producer.

In accordance with a preferred embodiment of the invention the hydraulic oil tank is so designed that, at an unfavorable arrangement of the masses with respect to their function but not with respect to weight distribution,

the oil tank changes or equalizes such unfavorable weight distribution and effects correct weight distribution. This result is obtained by making the thickness or vertical extension of the oil tank diflerent at different portions of its base area. It is of advantage to make the oil tank in the form of a plate generally having small thickness but having great thickness at the locations where additional weight is required.

In order to make the tank capable of supporting heavy loads, its walls may be braced and/or stiffened by ribs, corrugations or the like.

The invention may be applied to plate tampers as well as to roller tampers. As with plate tampers there can be produced a travel component by directed vibrations, the hydraulic system need be designed only for the operation of the vibration generator. This is not possible with roller tampers which must either by pushed by hand or by a separate drive for the rollers, for example, as shown in our aforementioned Patent No. 3,280,712.

According to the invention this separate drive is obtained by connecting two hydraulic drive circuits to the flat oil tank which circuits are controlled by a regulating valve which is preferably mounted on the oil tank and forms part of the mass. One of said circuits admits oil to a hydraulic motor driving the vibration generator, and the second circuit supplieds oil to hydraulic motor means acting on the hubs of the rollers. It is preferred to drive hydraulically a worm gear which is operatively connected to the rollers.

The novel features which are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, and additional objects and advantages thereof will best be understood from the following description of embodiments thereof when read in connection with the accompanying drawing, wherein:

FIG. 1 is a part sectional, diagrammatic elevational view of a soil compactor in the form of a plate tamper, according to an embodiment of the invention; and

FIG. 2 is a part sectional, diagrammatic elevational view of a modified soil compactor in the form of a roller tamper.

Referring now particularly to FIG. 1 of the drawing, there is provided a ground contact plate 1, that carries a shaking device or vibration generator 2, and shaped above it there is supported a support plate 4 which also serves as an oil tank and is connected to the ground contact plate 1 by means of springs 3. A driving motor 6, a pump 5, a regulating valve 42 and a steering means 60 constitute masses mounted on the support plate 4.

The motor 6, by way of example chosen, is in the form of an internal combustion engine and drives the pump 5 which is part of the hydraulic plant. The pump 5 draws oil from the tank 4 through a conduit 50 and forces the oil through conduits '51, 52 and 58 to a hydraulic motor 21 from which the oil is returned to the oil tank 4 through conduits '59 and 53. The conduits 51 to '53 are rigid, while the conduits 58, 59 are flexible. The hydraulic motor 2 1 drives an unbalance means, such as an imbalanced wheel 20.

The major portion 40 of the oil tank formed by the support plate 4 is quite thin and fiat. A portion 41 of the oil tank 4 is shown to be of much greater vertical extension than the part 40: in this way the oil tank 4 can be made capable of equalizing the weight acting on the support plate. By providing relatively high portions 41 of the oil tank at correct locations, uneven weight distribution caused by other masses, like the motor 6, the pump 5 or the steering means 60, can be equalized. The high portion 41 of the tank may be provided with heat radiating fins 4'10.

The operation of the plate type tamper of FIG. 1 is as follows:

After starting the motor 6, the pump operatively connected thereto is put in operation. The regulating valve 42 has two positions. When a handle 420 for operating the valve is in neutral position, the oil circulates from the tank 4 through the pump 5 and back to the tank 4. When the handle 420 is in active position, the oil flows clockwise from the tank 4 through the conduit 50, the pump 5, the conduit 51, the valve 42, the conduit 58, the hydraulic motor 21, and through the conduits S9 and 53 to the tank portion 41.

The motor 21 drives the imbalanced wheel 20 which produces a vibrating motion of the ground plate *1. This motion also has a directional component jumpingly advancing the tamper. The support plate 4 moves relative to the ground plate 1 which movement is permitted by the flexible conduits 58 and '59. The hydraulic system can easily be so designed that at a difierent position of the handle 420 the tamper moves in the opposite direction.

The oil tank 4 forming the support plate is preferably a self-supporting structure and is provided 'with stiffened walls to accomplish this. The oil tank may have a bottom wall and a top wall which are connected by stays 400.

The shaking deivce or vibration generator 2 may be in the form of a conventional counterrotation or pendulum oscillator. A plurality of unbalance means 20 may be simultaneously or alternatively driven. Such arrangements are conventional and are not described in detail. The motor 6 need not be an internal combustion engine, and an electric motor may be used instead.

The invention may be equally successful applied to roller tampers as shown in FIG. 2. Like parts are designated by linke numerals in FIGS. 1 and 2.

The roller tamper comprises two roller drums 7 that 2', these parts are rigidly connected by means of two act as ground contact means, and a vibration generator lateral shields 8. Masses formed by the motor 6, the pump 5 and a steering means 60 are arranged on a support plate 4 which is resiliently connected by means of springs 80 to the lateral shields 8.

In the roller tamper shown in FIG. 2 not only the vibration generator 2 but also the roller drums 7 are hydraulically driven. In order to reduce the speed of rotation of the drums 7, a worm gear system is provided comprising a hydraulic motor 70, two worms 72 and two worm wheels 73 which are mounted on the axles of the rollers 7.

The conduits of the hydraulic system comprise flexible portions 43, 46, 47 and 4 9' and rigid portions 44, 45, 48 and 49. The latter may also be made flexible.

Starting of the roller tamper of FIG. 2 is carried out like that of the plate tamper shown in FIG. 1. After setting the valve 42, the oil circulates clockwise, in one stream from the oil tank 4 whose center portion is relatively high through the valve 42, the flexible conduit 43, and the rigid conduit 44 to the hydraulic motor 21 and therefrom back to the oil tank through the rigid conduit 45 and the flexible condut 46. The second stream flows from the valve 42 through the flexible conduit 47 and the rigid conduit 48 tothe hydraulic motor 70 and therefrom back to the tank 4 through the rigid conduit 49 and the flexible conduit 49. In this way the vibrating apparatus as well as the travel drive of the roller tamper are operated by a common hydraulic system.

The invention is also applicable to roller tampers wherein the hydraulic system drives the vibrating apparatus only.

At least a part of the conduits connected to the oil tank are flexible and are preferably made of synthetic material which is oil resistent and bendable.

'We wish it to be understood that we do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

Having thus described the invention, What we claim as new and desire to be secured by Letters Patent is as follows:

1. A tamper for compacting ground, comprising a driving motor, a hydraulic plan comprising an oil pump in driven connection with said driving motor, an oil tank, ground contact means, a vibration generator including a hydraulic motor rigidly connected to said ground contact means, first conduit means connected to said oil tank and to said oil pump for conducting oil from said tank to said oil pump, second conduit means connected to said oil pump and to said hydraulic motor for conducting oil from said oil pump to said hydraulic motor, third conduit means for returning oil from said hydraulic motor to said oil tank, said oil tank forming a support plate, at least said driving motor and a part of said hydraulic plant being mounted on said oil tank for increasing the mass thereof, and resilient means connected to said ground contact means and to said oil tank for resiliently connecting said oil tank to said ground contact means.

2. A tamper as defined in claim 1 wherein said ground contact means has a plate like configuration.

3. A tamper as defined in claim 1 wherein said ground contact means comprises at least one roller drum.

4. A tamper as defined in claim 1 wherein said oil tank is substantially coextensive with the area covered by said ground contact means.

5. A tamper as defined in claim 1 wherein said oil tank extends vertically substantially for the same distance throughout.

6. A tamper as defined in claim 1 wherein different parts of said oil tank extend for difierent vertical distances.

7. A tamper as defined in claim 1 wherein said oil tank has stiffened walls.

8. A tamper as defined in claim 1 wherein said oil tank includes a bottom wall and a top wall, and supporting stays therebetween.

9. A tamper as defined in claim 1 wherein said hydraulic plant comprises a regulating valve interposed in said second conduit means for controlling the oil flow therethrough, said valve being mounted on said oil tank for increasing the mass thereof.

10. A tamper as defined in claim 9, wherein said ground contact means is formed by two roller drums, hydraulically actuated drive means being operative connected to said roller drums for rotating said drums, fourth conduit means being provided between said regulating valve and said hydraulically actuated drive means for conducting a controlled flow of oil to said drive means, and fifth conduit means being connected to said hydraulically actuated drive means and said oil tank for returning oil from said drive means to said tank.

11. A tamper according to claim 10 wherein said hydraulically actuated drive means comprise a worm gear.

No references cited.

JACOB L. NACKENOFF, Primary Examiner.

US. Cl. X.R. 

